docs: def find_version(fname):
      """Attempts to find the version number in the file names fname.
      Raises RuntimeError if not found.
      """
      version = ""
      with open(fname, "r") as fp:
          reg = re.compile(r'__version__ = [\'"]([^\'"]*)[\'"]')
          for line in fp:
              m = reg.match(line)
              if m:
                  version = m.group(1)
                  break
      if not version:
          raise RuntimeError("Cannot find version information")
      return version